Pt nanoparticles functionalized hydrogen-bonded organic frameworks: A three-in-one nanozyme for colorimetric...

To meet the increasing demands for highly active and stable nanozymes for bioanalysis, Pt nanoparticles (NPs) were successfully supported on the surface of hydrogen-bonded organic frameworks (Pt/HOFs) to obtain a stable, multifunctional and highly active nanozyme for the colorimetric detection of alkaline phosphatase (ALP). Through a redox reaction, Pt precursors are reduced to ultrasmall Pt NPs that are loaded on HOFs. The Pt/HOFs nanozyme showed excellent oxidase-like, peroxidase-like and some catalase-like activity. To avoid the signal instability caused by H₂O₂ decomposition, the oxidase-like activity of Pt/HOFs was applied for the detection of ALP using 3,3', 5,5 '-tetramethylbenzidine (TMB) as a chromogenic substrate. When the substrate L-ascorbic acid 2-phosphate (AAP) is present, ALP can catalyze AAP to produce strongly reductive ascorbic acid (AA). AA can reduce the oxidation product of TMB. Therefore, a colorimetric sensing strategy for ALP detection was constructed. The linear range of the strategy was from 0.5 to 8 mU mL^-1, and the detection limit was 0.46 mU mL^-1. Finally, the strategy was successfully applied to the detection of ALP in human serum, which provided a reliable strategy for the colorimetric detection of clinical ALP. This study not only presents a simple approach to maintain the high activity of nanoparticle-based nanozymes, but also expands the application of multifunctional HOF-based materials for future applications.